Question: The arithmetic sequence $(a_i)$ is defined by the formula: $a_i = -1 + 5(i - 1)$ What is $a_{17}$, the seventeenth term in the sequence?
Explanation: From the given formula, we can see that the first term of the sequence is $-1$ and the common difference is $5$ To find $a_{17}$ , we can simply substitute $i = 17$ into the given formula. Therefore, the seventeenth term is equal to $a_{17} = -1 + 5 (17 - 1) = 79$.